Japan Geoscience Union Meeting 2019

Presentation information

[J] Oral

A (Atmospheric and Hydrospheric Sciences ) » A-AS Atmospheric Sciences, Meteorology & Atmospheric Environment

[A-AS04] Atmospheric Chemistry

Wed. May 29, 2019 9:00 AM - 10:30 AM 102 (1F)

convener:Tomoki Nakayama(Graduate School of Fisheries and Environmental Sciences, Nagasaki University), Yoko Iwamoto(Graduate School of Biosphere Science, Hiroshima University), Sakae Toyoda(Department of Chemical Science and Engineering, Tokyo Institute of Technology), Nawo Eguchi(Kyushu University), Chairperson:Fumiko Nakagawa(名古屋大学)

9:30 AM - 9:45 AM

[AAS04-02] The 60 years history of atmospheric formation pathways responsible for sulfate based on triple oxygen isotopic composition of sulfate preserved in SE-Dome ice core

*Shohei Hattori1, Iizuka Yoshinori2, Koji Fujita3, Ryu Uemura4, Sakiko Ishino1, Naga Oshima5, Nozomi Suzuki1, Sumito Matoba2, Asuka Tsuruta1, Joel Savarino6, Naohiro Yoshida1 (1.Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2.Institute of Low Temperature Science, Hokkaido University, 3.Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan., 4.Department of Chemistry, Biology, and Marine Science, Faculty of Science, University of the Ryukyus, 5.Meteorological Research Institute, 6.Institut des Geoscience de l’Environnement, Universite Grenoble Alpes/CNRS)

Keywords:stable isotope, Sulfate, Triple oxygen isotopes, Chemical feedback

The atmospheric sulfate is important for both climate change and air quality; it influences radiation forcing and cloud’s lifetime, and accounts for major components in fine particulate matter mass in urban regions with affecting visibility and public health. The emitted SO2 is oxidized by OH radicals in the gas-phase, but modeling studies suggest that the large proportions (~80%) of global sulfate production were occurred in the aqueous-phase. However, the treatment of aqueous-phase in cloud pH set in atmospheric chemistry-transport models had the largest impact for atmospheric sulfate concentrations. Due to the lack of critical understanding for the chemical processes responsible for sulfate production, it is difficult to predict future changes in [SO42−] and its effects on climate and air quality.

To help address this, here we use mass-independent oxygen isotopic composition (Δ17O) of sulfate providing insight into past oxidation pathways responsible for sulfate formation. We present Δ17O of SO42− obtained from a 90.45 m depth ice core drilled at a high-elevation dome site in southeast Greenland called SE-Dome, covering the last 60 years. We found that Δ17O of SO42− with low during the 1960s-1970s and high in after the 2000s. This increase in Δ17O of SO42− indicates that sulfate formation pathways responsible for sulfate changed after 1960 to the present along with declining SO2 emission. In the presentation, we will discuss the enhanced role of a oxidation processes contributing to increase Δ17O of SO42−, and its implication to the changes in atmospheric chemistry though the changes in anthropogenic activities. This provides insight into direct and indirect effects of anthropogenic activities to the air quality by changing sulfate formation pathways. These functions, so called “chemical feedback", should be considered for making efficient mitigation policy for climate change and air quality by controlling emission of anthropogenic pollutants.